1. Field of the Invention
This invention relates to a balloon catheter suited for use with a guiding wire that passes through a guiding wire lumen of the catheter shaft from the proximal end to the distal end and through a balloon.
2. Background Information
A catheter that has a guiding wire that passes through a guiding wire lumen of the catheter shaft is referred to as a so-called “over-the-wire catheter”. This catheter construction comprises a catheter shaft having an inflatable balloon at its distal end. At the opposite proximal end, normally a connecting piece is arranged. Further, the known catheter comprises a guiding wire extending through a guiding wire lumen of the catheter shaft from the proximal end to the distal end and through the balloon. Finally, an inflation or deflation lumen is provided in the catheter shaft, said lumen extending from the proximal end of the catheter shaft to the balloon. Air or liquid may be supplied or discharged through said lumen for expanding the balloon.
If such a balloon catheter is to be inserted into a heart artery, an outer guiding catheter is at first pushed with its curved tip through the aorta, usually starting from the thigh, to the heart artery to be treated, in which e.g. a stenosis exists, which shall be expanded by the balloon catheter and possibly stabilized by a simultaneously implanted stent. The tip of the guiding catheter is thereby temporarily fixed in the region of the branching of the heart artery to be treated from the arch of the aorta. Into said guiding catheter, the guiding wire is subsequently inserted until its tip has passed the stenosis. In the following, the catheter shaft of the balloon catheter is inserted through the guiding wire into the aorta and the vessel to be treated, until the balloon stops in the region of the stenosis.
For this type of balloon catheter, the guiding wire must have approximately the double length of the catheter, as the catheter at first has to be threaded on the guiding wire outside the patient's body.
In a further known balloon catheter construction, a catheter shaft is provided having a shaft portion extending from the connecting piece and being composed of metal, which has a full cross section except for the inflation. Said portion (also referred to as hypotube) is followed by a plastics portion extending to the balloon in which a guiding wire volume is provided besides the inflation volume, which, however, has an outlet opening in front of the metal shaft portion, said outlet opening being positioned relatively close in front of the balloon. This makes it possible to use a substantially shorter guiding wire. In addition, this type of catheter shows a higher stiffness due to the metal shaft portion disposed in the proximal region, which enhances the so-called pushability.